Role of Clostridia community in fermented grains during Luzhou-flavor liquor production

Abstract:

[Objective] The succession of community structure and potential functional composition of Clostridia in fermented grains of Luzhou-flavor liquor during the fermentation process were studied. [Methods] Real-time quantitative PCR combined with high-throughput sequencing was used to study the dynamics of Clostridia community in fermented grains. 16S rRNA genehigh-throughput sequencing using specific primers was conducted to reveal the succession of Clostridia community. Biomarkers were located on OTU-level through LEfSe analysis. Predictive functional composition of Clostridia community was studied using PICRUSt. [Results] The biomass and relative abundance of Clostridia community reached their maxima at 14 d (3.46×107 copies/g) and 20 d (6.67%), respectively. Clustering analysis showed that the structure of Clostridiacommunity in 7-dsample was significantly different from that in other samples. 17 OTUs were located as biomarkers, and the BLAST results of these OTUs indicated that most of them represented unclassified bacteria. PICRUSt analysis showed that Clostridia community mainly participated in amino sugar and nucleotide sugar metabolism and pentose phosphate pathway followed by fructose and mannose metabolism, citrate cycle, glycolysis, propanoate and butanoate metabolism. [Conclusion] The biomass and the relative abundance of Clostridia community in fermented grains of Luzhou-flavor liquor reached their maxima after being fermented for two to three weeks. The structure of Clostridia community shifted significantly during the first week of fermentation and then gradually recovered in the following two weeks. A number of predictive functional genes related to the metabolism of flavor compounds such as propanoate and butanoate were detected in Clostridia community during 14?21 d of fermentation.

Key words:Luzhou-flavor liquor, Fermented grains, Clostridia community, Succession, Functional composition